The Hazmat suit in Fallout 4 allows you to withstand any amount of radiation especially in locations like The Glowing Sea where the radiation levels are insanely high. Of course, you can use a power armor as well to navigate such areas as it will provide protection as well, but if you don’t have one or lack fusion cores, the Hazmat suit is your best bet.
Now there are many locations where you can find the Hazmat suit. The easiest one is to do a side quest from Bobbi in Goodneighbour and eventually you will reach a garage where you can take an enemy’s Hazmat suit. You can also buy one in Diamond City.
In case you don’t want to do either of them, here’s where you can find the Hazmat suit. You have to go to Hugo’s hole located in the eastern section of the map. The locations are in the video below. (Thanks, bk – The Laid Black Gamer)